The present invention relates to press apparatus and, more particularly, to a clamping apparatus for holding molds within a press such as may be used for vulcanizing tires.
One type of press commonly used for vulcanizing tires includes an upper and lower platen having opposing faces and a pair of mold halves wherein each mold half includes a base mounted to the face of a respective platen. The platens are movable toward and away from each other such that the mold halves may assume an open position to receive an uncured or green tire and a closed position for vulcanizing the tire within the press. The necessary heat for vulcanizing the tire is usually provided by the platens which are heated through a circulating steam source wherein heat is transferred from the face of each platen to the base of a respective mold half. In addition, steam is used to heat a diaphragm located inside the uncured tire thereby to increase the internal tire temperature as well as provide controlled pressure to press the uncured tire into the mold halves such that the uncured tire is transformed into the final appearance characteristics of the tire as defined by the design pattern formed in the inside surfaces of the mold halves.
Those skilled in the art will be aware that other methods of heating tire vulcanizing molds are available. For example, the platens may be heated electrically rather than with steam or the molds may be heated directly by placing them in a heated pressure chamber such as is done by steam dome press. Alternatively, the molds may be designed with hollowed out cavities for receiving steam whereby the mold may be heated directly by the steam such as is provided by jacketed mold presses.
For the purpose of simplifying the present discussion and disclosing the novelty and advantages of the present invention, reference will be made in the following descriptive portions to a press having platens which are formed as the mold heating means and in which means are provided for clamping the mold halves to the platens. However, it should be understood that other methods of heating molds currently being used in the tire industry are equally applicable to the present invention.
When it becomes necessary to remove a mold from the press, either for the purpose of repairing the mold or to replace it with another mold, the mold halves are first moved to their mating or closed position and a plurality of bolts holding each mold half to its respective platen must then be removed. The upper platen is then raised away from the mold halves and the mold halves may then be removed from the press by a lifting device such as a forklift and taken away for repair, cleaning or for storage.
The above procedure has proven to be difficult, time consuming and dangerous since a typical mold change operation is often performed upon a pair of molds that have just completed their production run and which may be at temperatures approaching 400.degree. F. Further, the installation of replacement molds is also a difficult operation in that the bolt holes on the molds must be accurately aligned with the holes in the platens, or an equivalent support structure on the press, before the bolts may be installed to fasten the molds to the press. The difficulty of this operation is increased by the extreme weight of the molds which prevents the molds from being easily manipulated into proper alignment with the press platens and usually requires the use of additional equipment such as hydraulic jacks, chains and wedges.
Thus, there is a need for providing means by which mold halves may be quickly removed from their respective supporting structures on the press. In addition, there is a need for means which facilitate positioning and clamping of replacement molds to a press without requiring plant personnel to move in and about the press structure which is usually hot.